End of year festivities are now in full swing with our focus on friends, family and food. In this blog, I look at how diet can affect your mental health, and share some healthy eating tips to get you through the silly season without the mood swings and guilt.

Does diet affect mental health?

If you’re in a negative mood, you’re more likely to choose indulgent, comfort foods that are sugary, fatty or salty instead of opting for nutritious options.

We have anecdotal evidence to support the notion that how you feel affects the foods you choose to eat.

Until recently, what was less understood was the causal relationship between food and how it affected mood.

The SMILES trial – evidence at last!

Associate Professor Felice Jacka, Deakin University researcher and founder of the International Society for Nutritional Psychiatry, and her team have recently conducted a small clinical trial of 67 people suffering symptoms of depression and found a link between diet and their mental health.

In the study, half of the participants were encouraged to follow a Modified Mediterranean Diet, which was constructed using existing dietary guidelines from Greece and Australia, traditional Mediterranean diet principles. Everyone was coached by a dietician. A comparison group of people with the same symptoms, were offered social support only.

The results of the SMILES study, published in the international journal BMC Medicine, showed that participants in the dietary intervention group had a much greater reduction in their depressive symptoms over the three-month period, compared to those in the social support group.

At the end of the trial, a third of those in the dietary support group met criteria for remission of major depression, compared to 8 percent of those in the social support group.

Jacka says,

“Research now suggests that depression and dementia are affected by the quality of our diets across the life course. Research also shows that adults who eat more unhealthy junk foods are at increased risk of depression.”

This is also the case in teenagers.

“We see a pretty clear dose-response relationships between their diet and level of mental health and wellbeing. In particular, those that had low scores on what we call an unhealthy dietary pattern were worse off, and those who had a higher score on the nutrient-dense dietary pattern were better off.”

What foods should I choose to improve mood?

The ‘bad-mood food’ culprits are what you might expect. As Jacka explains,

“Highly-processed snack and takeaway food products, rich in tasty fat and sugar, have now displaced much of the fruit, vegetables and other nutritious, unprocessed foods in our diets.”

Healthy, nutrient-dense dietary patterns, such as the Mediterranean diet, seem to protect against developing depression, and also dementia. Jacka says,

“The strongest evidence-base we have is for the Mediterranean diet, and it is what we should be advocating for everyone.”

A Mediterranean type diet (which is not red wine based!) is characterised by high consumption of plants (vegetables, fruits, legumes, nuts, and whole grains), is rich in healthy fats from generous consumption of fish and olive oil, is low in red meat and dairy, and allows for moderate consumption of red wine with meals.

Tips for healthy eating over the festive season.

Tis the season to be jolly!

Here are some easy brain-healthy choices you can make to keep you feeling joyful at your next BBQ or end of year party:

Instead of only snacking on chips, try a few raw nuts too (just not the salted and roasted kind!).

Load up your plate with salad or veggies first — you’ll leave less room for meat, bread or potatoes.

Swap the BBQ lamb chop or steak for salmon. Omega-3 fats in fish reduce inflammation, which may contribute to an increased risk of depression or anxiety.

Add some legumes (beans, chickpeas or lentils) to your plate. Your gut will love the extra fibre, and evidence is building that a healthy gut microbiome is linked to better mental health.

High-quality extra-virgin olive oil seasoned with balsamic vinegar is delicious for dipping wholegrain bread, and is a healthy alternative to butter or margarine.

Enjoy prawns and turkey. Both are rich in tryptophan an essential amino acid that is the precursor for the neurotransmitter (brain chemical) serotonin.

Swap the pavlova for fresh fruit (or at least choose both!). Or, if you must indulge, save the sweet treats for a special occasion like Christmas day.

Cheers! Enjoy a glass of red wine with friends and family. Social connection is one of the best protective factors against mental health problems and cognitive decline.

A version of this post was originally published in ABC Active Memory. The site retired in 2017.